[On how, after the Flood, all those millions of animals returned back to their respective homes.]

He had 2 of every animal. That's a good question. However, I bet the oceans didn't appear until after the Flood. So they hopped, walked, crawled, or whatever they did. I think the oceans were created when the water came shooting from the crust.

Yep, not only that 40 days and nights of rain were allegedly enough to fill 75% of earth with water, no, it gets even better:

This would mean a rainstorm against which hurricane Katrina was a slight breeze in comparison. Any boat made of wood in the size of the ark would have survived perhaps 3 milliseconds before transformed into a mess of wooden smithereens and its crew and passengers drowning immediately.